el-get and vimpulse

We all know the (lovely?) feature of Vim to treat no files ever as binary by default. Now el-get is using url-retrieve to fetch tar files and using write-file to write it. Now either vimpulse (or Viper?) is appending a trailing \n which makes tar complain about trailing garbage exiting with code 2. How would you recommend to solve this issue? I didn't start reading much vimpulse / Viper code yet. Maybe there is a simple option (?) Marc Weber